Sympathetic nervous activity to brown adipose tissue increases in cold-tolerant mice

Kawate, R; Talan, Mark I.; Engel, Bernard T.

doi:10.1016/0031-9384(94)90080-9

Cited by 32 publications

(19 citation statements)

References 17 publications

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“…Surprisingly, between successive rounds of cold exposure in the ICE protocol, we observed re-expansion of adiposity to a level beyond the basal level of the preceding cycle. This finding of a net increase in fat mass in our ICE mice is in line with a previous mouse study [19], but is at variance with several ICE rodent studies [17], [18], [20]–[22] and the two recent human studies, which either detected a reduction of body fat after 6 weeks of daily 2 h cold exposure [23] or observed no change in adiposity after 10 days of a similar ICE protocol (personal communication with Dr. Wouter D. Van Marken Lichtenbelt) [24]. The discordance is likely multifactorial and may include differences in species and experimental protocols.…”

Section: Discussionsupporting

confidence: 92%

Intermittent Cold Exposure Enhances Fat Accumulation in Mice

et al. 2014

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Due to its high energy consuming characteristics, brown adipose tissue (BAT) has been suggested as a key player in energy metabolism. Cold exposure is a physiological activator of BAT. Intermittent cold exposure (ICE), unlike persistent exposure, is clinically feasible. The main objective of this study was to investigate whether ICE reduces adiposity in C57BL/6 mice. Surprisingly, we found that ICE actually increased adiposity despite enhancing Ucp1 expression in BAT and inducing beige adipocytes in subcutaneous white adipose tissue. ICE did not alter basal systemic insulin sensitivity, but it increased liver triglyceride content and secretion rate as well as blood triglyceride levels. Gene profiling further demonstrated that ICE, despite suppressing lipogenic gene expression in white adipose tissue and liver during cold exposure, enhanced lipogenesis between the exposure periods. Together, our results indicate that despite enhancing BAT recruitment, ICE in mice increases fat accumulation by stimulating de novo lipogenesis.

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Section: Discussionsupporting

confidence: 92%

Intermittent Cold Exposure Enhances Fat Accumulation in Mice

et al. 2014

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“…Nonshivering thermogenesis in brown fat is activated by the SNS through the release of catecholamines. Studies have shown that SNS activation during nonshivering thermogenesis is necessary for cold tolerance in mice (8) and that elevated plasma catecholamine levels coincide with cold temperature-induced hypertension in rats (3,14). Furthermore, rats reared at 18°C exhibit augmented development of the sympathetic ganglion relative to rats reared at 30°C (12), suggesting that temperature-induced SNS demands are capable of manifesting their effect on SNS development.…”

Section: Discussionmentioning

confidence: 99%

Effect of ambient temperature on cardiovascular parameters in rats and mice: a comparative approach

Swoap

Overton²,

Garber³

2004

American Journal of Physiology-Regulatory, Integrative and Comp

114

109

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of Ͻ6°C or Ͼ29°C have been shown to induce large changes in arterial blood pressure and heart rate in homeotherms. The present study was designed to investigate whether small incremental changes in T a, such as those found in typical laboratory settings, would have an impact on blood pressure and other cardiovascular parameters in mice and rats. We predicted that small decreases in T a would impact the cardiovascular parameters of mice more than rats due to the increased thermogenic demands resulting from a greater surface area-to-volume ratio in mice relative to rats. Cardiovascular parameters were measured with radiotelemetry in mice and rats that were housed in temperaturecontrolled environments. The animals were exposed to different T a every 72 h, beginning at 30°C and incrementally decreasing by 4°C at each time interval to 18°C and then incrementally increasing back up to 30°C. As T a decreased, mean blood pressure, heart rate, and pulse pressure increased significantly for both mice (1.6 mmHg/°C, 14.4 beats ⅐ min Ϫ1 ⅐°C Ϫ1 , and 0.8 mmHg/°C, respectively) and rats (1.2 mmHg/°C, 8.1 beats ⅐ min Ϫ1 ⅐°C Ϫ1 , and 0.8 mmHg/°C, respectively). Thus small changes in T a significantly impact the cardiovascular parameters of both rats and mice, with mice demonstrating a greater sensitivity to these Ta changes. blood pressure; heart rate; standard deviation of the interbeat interval; radiotelemetry THE EXTERNAL ENVIRONMENT can have a substantial impact on the cardiovascular system. Exposure of humans (1,7,18,32), rats (2,3,14,20), and mice (22) to cold ambient temperature (T a ) results in elevated blood pressure and heart rate. It appears as if the tachycardia and hypertension are the indirect result of sympathetic nervous system (SNS) activation of thermoregulatory mechanisms because elevated plasma norepinephrine (NE) levels correlate with elevated blood pressure in the cold (7,14,17,32). Furthermore, propranolol, a ␤-adrenergic blocking agent, can blunt or completely reverse the cardiovascular effects of cold exposure (21). Cold-induced activation of the SNS, in turn, appears to elevate blood pressure through activation of the renin-angiotensin system (RAS). Blockade of the RAS systemically (19), centrally (15,16,22), or genetically in an angiotensinogen knockout mouse model (23) blunts or prevents cold-induced hypertension, suggesting that RAS signaling pathways are necessary for T a -induced effects on blood pressure.Elevation of T a beyond typical housing temperatures also impacts the cardiovascular system. Warming rats (31) and mice (30, 31) from 23°C to 28 -31°C, closer to, if not within, their thermoneutral zone (TNZ) results in a drop in heart rate and blood pressure. Metabolic rate in homeotherms is at its minimum in the TNZ, which is approximately 28 -31°C for rodents (4). Animals with smaller body sizes have higher surface area-to-volume ratios and thus typically exhibit warmer TNZs. At temperatures below the TNZ, nonshivering thermogenesis is stimulated by increased sympathetic activity to offset the...

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“…Both a centrally mediated enhancement of the level of sympathetic outflow to BAT (Kawate et al, 1994) and an upregulation of BAT metabolic processes contribute to these enhanced thermogenic responses. The amplified BAT thermogenesis in cold acclimation is lost, however, if the interval between cold exposures is increased from 2 to 4 weeks (Talan and Engel, 1988), indicating a return to normal conditions in the absence of the conditioning cold stimulus.…”

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confidence: 99%

Reduced Rearing Temperature Augments Responses in Sympathetic Outflow to Brown Adipose Tissue

Morrison¹,

Ramamurthy²,

Young

2000

J. Neurosci.

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Sympathetic outflow to brown adipose tissue (BAT) contributes to both thermoregulation and energy expenditure in rats through regulation of BAT thermogenesis. Acute cold exposure in mature animals augments BAT thermogenesis; however, the enhanced BAT thermogenic response returns to normal shortly after cessation of the cold exposure. In this study, we sought to determine whether cold exposure in early neonatal life could induce enhanced responses in the sympathetic outflow to BAT and whether this altered sympathetic regulation would be sustained after the cold stimulus was removed. BAT sympathetic nerve activity (SNA) was recorded in urethane-chloraloseanesthetized, artificially ventilated rats that were raised from birth in either 18 or 30°C environments and then, at 8 weeks of age, were maintained in 23°C for at least 4 weeks. An acute hypothermic stimulus, disinhibition of a brainstem thermogenic network in the raphe pallidus, or electrical stimulation in this raphe site produced increases in BAT SNA that were twice as great in rats reared at 18°C as in those reared at 30°C. The norepinephrine content of the interscapular BAT (IBAT) and the number of sympathetic ganglion cells projecting to interscapular BAT were 70% greater in the 18°C-reared rats. We conclude that neonatal exposure to a cold environment induces a permanent developmental alteration in the capacity for sympathetic stimulation of BAT thermogenesis that may be mediated, in part, by a greater number of sympathetic ganglion cells innervating BAT in coldreared animals.

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Sympathetic nervous activity to brown adipose tissue increases in cold-tolerant mice

Cited by 32 publications

References 17 publications

Intermittent Cold Exposure Enhances Fat Accumulation in Mice

Intermittent Cold Exposure Enhances Fat Accumulation in Mice

Effect of ambient temperature on cardiovascular parameters in rats and mice: a comparative approach

Reduced Rearing Temperature Augments Responses in Sympathetic Outflow to Brown Adipose Tissue

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